This view of the twilight sky and Martian horizon taken by NASA's Curiosity Mars rover includes Earth as the brightest point of light in the night sky. Earth is a little left of center in the image, and our moon is just below Earth.

This frame from an animation from NASA's Mars rover Curiosity shows the rover drilling into rock target 'Cumberland.' The drilling was performed during the 279th Martian day, or sol, of the Curiosity's work on Mars (May 19, 2013).

This image from the Mars Hand Lens Imager on NASA's Mars rover Curiosity shows the patch of rock cleaned by the first use of the rover's Dust Removal Tool (DRT). The tool is a motorized, wire-bristle brush on the turret at the end of the rover's arm.

The two bodies in this portion of an evening-sky view by NASA's Mars rover Curiosity are Earth and Earth's moon. The rover's Mast Camera (Mastcam) imaged them in the twilight sky of Curiosity's 529th Martian day, or sol (Jan. 31, 2014).

This engineering drawing shows various components needed to support tools at the end of the arm on NASA's Curiosity rover, including: calibration targets for helping instruments set their baseline levels.

This engineering drawing shows the five devices that make up the turret at the end of the arm on NASA's Curiosity rover. These include: the drill for acquiring powdered samples from interiors of rocks.

This engineering drawing shows the location of the arm on NASA's Curiosity rover, in addition to the arm's turret, which holds two instruments and three tools. The arm places and holds turret-mounted tools on rock and soil targets.

Tracks from the first drives of NASA's Curiosity rover are visible in this image captured by the High-Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. The rover is seen where the tracks end.

The left eye of the Mast Camera (Mastcam) on NASA's Mars rover Curiosity took this image of the camera on the rover's arm, the Mars Hand Lens Imager (MAHLI), during the 30th Martian day, or sol, of the rover's mission on Mars (Sept. 5, 2012).

This 3D image from NASA's Curiosity was taken from the rover's Bradbury Landing site inside Gale Crater, Mars. Between the rover on the right, and its shadow on the left, looms the rover's eventual target: Mount Sharp.

NASA's Mars rover Curiosity drove about 70 feet (about 21 meters) on the mission's 21st Martian day, or sol (Aug. 30, 2012) and then took images with its Navigation Camera that are combined into this scene, which inclues the fresh tracks.

Details such as the shadow of the mast on NASA's Mars rover Curiosity appear in an image taken Aug. 17, 2012, by the HiRISE camera on NASA's Mars Reconnaissance Orbiter, from more directly overhead than previous HiRISE images of Curiosity.

The Chemistry and Camera (ChemCam) instrument on NASA's Mars rover Curiosity used its laser to examine side-by-side points in a target patch of soil, leaving the marks apparent in this before-and-after comparison.

On Aug. 28, 2012, during the 22nd Martian day, or sol, after landing on Mars, NASA's Curiosity rover drove about 52 feet (16 meters) eastward, the longest drive of the mission so far. The drive imprinted the wheel tracks visible in this image.

This image shows a close-up of track marks left by NASA's Curiosity rover. Holes in the rover's wheels, seen here in this view, leave imprints in the tracks that can be used to help the rover drive more accurately. The imprint is Morse code for JPL.

The straight lines in Curiosity's zigzag track marks are Morse code for JPL. The 'footprint' is an important reference mark that the rover can use to drive more precisely via a system called visual odometry.

This image shows a close-up of track marks from the first test drive of NASA's Curiosity rover. The rover's arm is visible in the foreground. A close inspection of the tracks reveals a unique, repeating pattern: Morse code for JPL.